232 MANUAL OF ZOOLOGY. 



the entire process being stated to occupy in some species as 

 much as two years, before maturity is reached. 



The Myriapoda are divided into two orders viz., the Chilo- 

 poda and the Chilognatha. 



ORDER I. CHILOPODA. This order comprises the well- 

 known carnivorous Centipedes and .their allies, and is charac- 

 terised by the number of legs being rarely indefinitely great 

 (usually from 15 to 20 pairs), by ttys composition of the 

 antennae out of not less than 14 joints (14 to 40 or more), and 

 by the structure of the masticating organs. These consist of 

 a pair of mandibles with small palpi, a labium, and two pairs 

 of" maxillipedes," or foot-jaws, of which the second is hooked, 

 and is perforated for the discharge of a poisonous fluid. There 

 is not more than one pair of legs to each somite, and the last 

 two limbs are often directed backwards in the axis of the body, 

 so as to form a kind of tail. The body in all the Chilopoda 

 is flattened. 



Scolopendra (fig. 78), Lithobius, and Geophilus are common 

 European genera of this order. The ordinary Centipedes of 

 this country are perfectly harmless, but those of tropical 

 regions sometimes attain a length of a foot, or more, and these 

 are capable of inflicting very severe, and even dangerous, 

 bites. 



ORDER II. CHILOGNATHA. This order comprises the vege- 

 table-eating Millipedes (lulidce) and the Gallyworms (Polydes- 

 mus). The order is characterised by the great number of legs, 

 each segment except the anterior ones bearing two pairs ; 

 by the composition of the antennae out of six or seven joints; 

 and by the structure of the masticating organs, which consist 

 of a pair of mandibles without palps, covered by a lower lip, 

 composed of the confluent maxillae. 



Fig. 79. Millipede (lulus). 



In the common Millipede (lulus) the body is composed of 

 from forty to fifty segments, each of which bears two pairs of 

 minute, thread-like legs. The lull of this country are of small 

 size, but an American species attains a length of more than 

 half a foot. 



DISTRIBUTION OF MYRIAPODA IN TIME. About twenty 

 species of Myriapoda are known as fossils, the oldest example 



